Cooperative and Geometry-Dependent Mechanochromic Reactivity through Aromatic Fusion of Two Rhodamines in Polymers

• DOI: 10.1021/jacs.2c07015
• Publication Date: 2022-09-07T21:17:21Z
• Authors: Mengjiao Wu; Yiran Li; Wei Yuan; Guillaume De Bo; Yi Cao; Yulan Chen
• Keywords: Reactivity; Rhodamine; Bond cleavage

The unique topological features of Piezo proteins underlie the lever-like cellular mechanotransduction mechanism. This knowledge inspires us to seek topological/geometric control mechanochromophores with unprecedentedly amplified, synergistic changes in polymers serve as ideal stress probes. Here, by judicious placement two spirolactam rings into aminobenzopyranoxanthene, a series stereo- and regio-isomeric rhodamine-like mechanophores are developed. With labile bonds closely coupled one rigidified scaffold, these π-fused bis-mechanophores enable mechanochromic polymers, featuring cooperative bond scission, low rupture force (lower than rhodamine), geometry-controlled ring-opening reactivity. Sonication, single-molecule spectroscopy experiments, density functional theory calculations provide insight force–color relationship rationalize how difference reactivity four isomeric is affected their molecular geometry thermodynamic equilibrium. Our strategy based on aromatic fusion bis-mechanophore promises modular approach for scission. Also, important insights internal external factors governing tandem mechanochemical reactions gained.